Heart valve disease is one of the main types of the current heart diseases, which can lead to major heart dysfunction and eventually requires the replacement of native heart valve with artificial heart valve. Bioprosthetic valve is a type of currently used artificial heart valve. Leaflets of the bioprosthetic valve are normally manufactured with an animal tissue membrane, such as pig artery valve or bovine pericardium, and then are sutured to the valve frame of the artificial heart valve after cross-linking and anti-calcification treatment.
In order to meet the function of the valve, each valve leaflet needs to meet particular requirements, for example, under some situation, different valve leaflets of one valve need to keep an identical thickness. For the surgically implanted bioprosthetic valve, according to the difference of the valve sizes, the required thicknesses of the valve leaflets are normally in the range of 0.3-0.6 mm. However, currently the thicknesses of the bovine pericardium collected from the slaughter houses are usually in the range of 0.1-0.8 mm and points of each piece of the bovine pericardium have different thicknesses. Therefore, usually only 1-2 pieces of qualified valve leaflets can be obtained from each piece of the pericardium, which results in a low yield. As for the transcatheter heart valve, in order to increase the transportability via blood vessels, the pre-installing diameter of the heart valve need to be reduced, which requires an even thin animal tissue membrane with thickness normally lower than 0.25 mm. Therefore, very few animal tissue membranes can be used for transcatheter heart valve, which leads to even lower yield.
Under other circumstances, in order to satisfy particular functions, it requires that points of the artificial valve leaflets have different thicknesses, which is difficult to be met by using the above mentioned method.
Therefore, the animal tissue membrane needs to be processed to meet the requirement for the thickness of the valve leaflets. U.S. Pat. No. 7,141,064 discloses a method for obtaining an animal tissue membrane with relatively uniform or relatively thin thickness by pressing during cross-linking treatment, the method can increase productivity. However, this method may be likely to straighten the corrugated fibers of the animal tissue membrane (such as bovine pericardium) and reduce its elasticity, and thereby affect bend and stretch effects of the valve leaflets during heart dilation and contraction, and also it is difficult to obtain valve leaflets with different thicknesses at different positions. Patent US2013110097, US20130116676 and US20130310929 disclose methods of processing a tissue in a state of crosslinking or semi-crosslinking by laser removal, scraping, grinding, etc. so as to make the thicknesses of the tissues uniform or reduced and to obtain a valve leaflet structure with different thicknesses at different spots. However, the animal tissue membrane used for the artificial heart valve is often a soft tissue, and when processing using the methods described above, the soft tissue tends to become deformed and corrugated, is hard to manipulate, and it is difficult to remove the residual debris of the tissue after processing.